Beekeeping is a wonderful hobby that can reap many rewards. It can even be a money earner when done the right way. There is a lot involved in keeping bees, but one thing that most people are unaware of is that the honeybee is susceptible to many different diseases and pests. It is the job, then, of the beekeeper to ensure that his or her colony is protected and treated should any incidences of disease or pests arise. In this article I will focus on acarine mites, or tracheal mites as they are also known as.
What are Acarine Mites?
In the early 1900s, the honeybee population on the Isle of Wight in the United Kingdom was decimated by a disease that became known as the Isle of Wight disease. The disease spread to other parts of the UK. In 1919, it was discovered that the Acarapis woodi parasite was present in the trachea of adult honeybees. It became clear at that time that it was these same tracheal mites that had led to the Isle of Wight disease earlier in the century.
With the spread of acarine mites to mainland UK and other parts of Europe, the US imposed a ban on the import of live bees in 1922. However, the disease continued to spread to other parts of the world and is believed to have reached the US in the 1980s via Mexico.
Acarine mites are tiny, oval shaped mites that live and reproduce in the trachea of adult honeybees. They enter the trachea of the bee through the spiracles (respiratory openings), which are found on the thorax or midsection of the bee.
Symptoms of Acarine Mite Infestation
If left untreated, acarine mites can lead to the death of the honeybee by clogging the breathing tubes and depriving them of oxygen. Bees that are affected by acarine mites often have distended abdomens and disjointed wings, leaving them unable to fly. The wings project outwards, and this symptom is known as ‘K-wing.’ The colony might also show signs of lethargy or excessive swarming.
It is vital, then, that the beekeeper be able to identify the presence of acarine mites in his/her colony so that he or she can act immediately to reduce the impact of the infestation.
How Acarine Mites Spread
Mature female acarine mites enter the spiracles of young bees, typically when these first emerge as it is during the first nine days that they are susceptible to infestation. As mentioned above, the acarine mites lay their eggs in the trachea and, upon hatching, the larvae feed on the blood of the host bee. Over the course of their transition to adulthood, the larvae molt several times. Upon maturation, they will be ready to infect new emerging bees.
Female mites lay around five to seven eggs over the course of three to four days. Male mites usually reach maturing within eleven to twelve days while female mites generally take around fourteen to fifteen days to reach full maturity. The mites mate within the same trachea in which they have hatched and matured.
Female mites typically leave the trachea to find new bee hosts at nighttime when the older bees are in closer contact with young bees. Upon leaving the trachea of the bee through its spiracle, the female acarine mite will attach itself to the tip of its host’s hair. Once the host brushes against another bee, the mite will transfer to the hair of the passing bee and enter its thorax through a spiracle.
Acarine mite infestation depends on close contact between foraging worker bees and young bees, which explains why female mites tend to leave their host to find a new one at night. It also explains why acarine mite infestation increases during periods of poor weather when worker bees are unable to leave the hive.
How to Detect Acarine Mites
If you have noticed that your bees seem lethargic and unable to fly properly, it is worth taking a close look to see if you can spot the signs of disjointed wings. While K-wings are common among bees affected by acarine mites, this symptom will not always present and its absence does not mean your bees are not affected. If your bees do have K-wings, you might notice that the hooks that normally hold the wings together have become detached.
If you own a microscope, you could detect an acarine mite infestation yourself by carrying out a dissection on a dead bee. Look at the primary trachea under the microscope at a magnification of at least 40.
If the bee in question had been infested by mites, the trachea will be affected by a dark staining or a patchy discoloration (caused by the feeding of the mites). An uninfected bee will have an intact trachea that is creamy-white in color.
When trying to detect acarine mite infestation, it is important to sample at the right time as the population of mites will vary from season to season. For example, you are far more likely to detect acarine mites during early spring, late fall, or winter, which is when bee populations tend to be at their lowest and when there is a high number of older bees.
Prevention and Treatment of Acarine Mites
It is difficult to prevent acarine mite infestation, but regular checking and cleaning can help. Fortunately, there are a couple of natural treatments available to tackle such an infestation and which will have no harmful impact on your bee colony.
Grease patties are a popular method for tackling an acarine mite infestation. This natural method involves mixing one-part solid vegetable shortening with two to three parts granulated or powdered sugar. Once mixed, the beekeeper can place a patty on the top bars of the hive. It is typically placed in the center as this is where it is most likely to come into contact with the bees. Some beekeepers add natural oil extracts such as spearmint or lemongrass to their patties to make them more attractive to the bees.
The bees ingest the sugar and in so doing pick up traces of shortening which in turn disrupts the female mite’s ability to find the young bees. The mite cannot survive for more than a few hours outside of the host, so grease patties are an effective way of tackling acarine mite infestations.
Menthol is another method of addressing an infestation of acarine mites. Menthol packets should be placed in the hive. However, where these are placed is temperature dependent.
As the menthol is exposed to specific air temperatures, it will vaporize and the colony fills with its fumes. The bees will breath the vapor, which will in turn kill the mites in their tracheae. It is important to keep the menthol in the hive for a period of two weeks to ensure all mites are exterminated. You will need two ounces of menthol for every two-story hive that you have.
Acarine or tracheal mite infestation is quite common among bee colonies. However, with vigilance and early intervention, you can ensure that your bee population remains healthy and productive.